This invention relates to the art of organo tin compounds, the art of stabilization of polymers, and the art of polythioethers and polythioformals. Poly(vinyl chloride) is relatively unstable to heat and light. Initiation by heat involves rupture of the carbon-chlorine bond adjacent to a structure such as terminal unsaturation which reduces its stability. Initiation by ultraviolet light which is absorbed at unsaturated structures also results in release of adjacent chlorine atoms. The chlorine radical formed by either initiating event then abstracts hydrogen to form HCl. The chain radical forms chain unsaturation with consequent generation of another chlorine radical. The presence of oxygen accelerates the process and serves to introduce ketonic structures in the chain.
Improvement in the heat and light stability requires the addition of stabilizers. Metallic salts of tin, lead, barium or cadmium are used. Oxides, hydroxides, or fatty acid salts have been commonly considered among the most effective. Dialkyl tin mercaptides particularly those derived from mercapto-acetic and mercaptopropionic esters are known among this group of stablizers.
The present invention provides novel dialkyl or diaryl tin mercapto derivatives which are suitable for use as stabilizers for poly(vinyl chloride).
Applicant is unaware of any art materially relevant to the invention of this application.